Eugene Donald Millikin was a United States Senator from Colorado who served as Senate Republican Conference Chairperson from 1947 to 1956. He entered the political world after his graduation from law school as the executive secretary to the Governor of Colorado in 1915. He continued to climb up the political ranks and by the 1940’s his rise was beginning.

Millikin was appointed on December 20, 1941, and subsequently elected on November 3, 1942, as a Republican to the United States Senate to fill the vacancy in the term ending January 3, 1945, caused by the death of Alva B. Adams. He was reelected in 1944 and 1950, and served in all during years 1941-1957.